1. Field of the Invention
The present invention relates to a micropattern transfer device for transferring a fine indented pattern formed on a surface of a stamper, onto a surface of a material to be transferred.
2. Description of the Related Art
Semiconductor integrated circuits have been made extremely smaller in recent years. When patterns of such extremely small circuits are formed, a high degree of accuracy is required in, for example, photolithography. However, micro-fabrication of those circuits with a high accuracy is now approaching its limit, because a scale of the micro-fabrication has nearly reached a wavelength of an exposing source itself for use in the micro-fabrication. To obtain an even higher accuracy, an electron beam writing technique, which is a technique relevant to a charged particle beam apparatus, has also been used instead of photolithography.
However, in forming patterns of extremely small circuits with an electron beam writing technique, the more patterns are drawn with the electron beam writing apparatus, the more time it takes for exposure. This is because the electron beam writing technique does not use a one-shot exposure with an exposing source such as an i-ray and an excimer laser. Hence, the more integrated the circuits become, the more time it takes for forming patterns, which results in a poor throughput.
To speed up the formation of patterns using an electron beam writing apparatus, a technique of electron beam cell projection lithography has been developed, in which electron beams are irradiated en bloc on a plurality of combined masks having various shapes. Such an electron beam writing apparatus for use in the electron beam cell projection lithography is necessarily large-sized and high-priced, because a structure of the apparatus becomes more complex, and a mechanism for controlling each position of the masks with a higher accuracy is required.
In forming patterns of extremely small circuits, imprint lithography has also been known, in which a stamper having a fine pattern complementary to a desired one is stamped onto a surface of a material to be transferred. The material to be transferred is, for example, a substrate having a resin layer thereon. The imprint lithography can transfer a microstructure having an indented width on a 25 nm scale or less onto the above-described resin layer on the substrate as a material to be transferred. More specifically, the resin layer (which may also be referred to as a “pattern forming layer”) includes a thin film layer formed on the substrate and a patterned layer composed of protrusions formed on the thin film layer. The imprint lithography has also been applied to creation of a pattern of recording bits for a large capacity recording medium and of a pattern of a semiconductor integrated circuit. For example, a mask for fabricating a large capacity recording medium substrate or a semiconductor integrated circuit substrate can be prepared by: using protrusions of a pattern forming layer using the imprint lithography as a mask; and etching portions of a thin film layer that expose as recesses of the pattern forming layer, and portions of a substrate that are immediately under the portions of the thin film layer.
In the imprint lithography, after the stamper is pressed against the resin layer formed on a surface of the material to be transferred, the stamper is separated therefrom, thus allowing a fine pattern on the stamper to be transferred onto the resin layer of the material to be transferred. At this time, a pressure and separation mechanism is required which allows repeated transfers using one and the same stamper without damaging a surface of the stamper or an edge of the material to be transferred such as a disk.
Japanese Laid-Open Patent Application, Publication No. 2004-335012 discloses a separating technique in which a portion of a stamper is suctioned and is pulled up from a material to be transferred. Japanese Laid-Open Patent Application, Publication No. 2002-197731 and Japanese Laid-Open Patent Application, Publication No. 2005-166241 disclose another separating technique in which a wedge is inserted between a stamper and a material to be transferred to make a gap, into which compressed air is fed, to thereby separate the stamper and the material to be transferred.
In those conventional techniques, a portion of a stamper or a material to be transferred may sometimes be locally loaded and may be thereby distorted or destructed. Thus, the conventional techniques are not suitable for a commercial mass production of a product, such as a large capacity recording medium substrate, in which repeated transfers are required using a single stamper.
The present invention has been made in an attempt to provide a micropattern transfer device capable of conducting repeated transfers using a single stamper without damaging the stamper or the material to be transferred.